In connectionless, packet-oriented networks, such as on the Internet or in networks based on ITU-T Standard H.323, no quality of service is guaranteed for connections between terminals in these networks. The quality of service also comprises the bandwidth and the transmission speed which is provided for a connection.
In the case of data or voice transmission in local area networks, that is to say in packet-oriented networks, the quality of service is assured by over-dimensioning the transmission system resources, since high bandwidths can be achieved inexpensively in local area networks. Frequently, subregions of local area networks—for example company-internal communication networks—are connected to one another to form other local area networks—a number of branch offices having a number of subsidiary branch offices. Since the subregions of the local area networks are usually provided at geographically different locations, leased lines are usually provided for the connections between these subregions. To assure a sufficient quality of service for connection paths routed between the subregions via these lines, there must only be as many connections routed via this connection path between the networks as there are available transmission system resources, a transmission system resource being demanded for each connection during connection initialization. In most applications, central units are provided which coordinate and monitor the connections within a subregion. By way of example, a packet-oriented multimedia communication system based on ITU-T Standard H.323 contains, for each of the subregions, gatekeepers which control and monitor data links and voice links—in the case of access to the Internet, also Voice over Internet links. Since the route through the network which is provided for each connection frequently runs via a plurality of subregions, it is a complex matter to monitor the bandwidth for each individual connection over the data paths for all connections beyond the respective subregions as well. To do this, it is necessary to know the exact switching paths for the connections within the subregions or within the local area network. However, the very high level of complexity means that such implementation is not economical in the gatekeepers of the multimedia communication systems based on Standard H.323.
Another alternative for assuring the quality of service in connections routed between subregions of a local area network is to over-dimension the connection paths between the subregions of the local area network. Such a solution requires a high level of additional technical and hence also financial input.